When a person wishes to radically change hair colour, in particular when they wish to obtain a lighter colour than the original colour, it is often necessary to bleach the hair. To do this, bleaching products are used. This bleaching step is optionally combined with a step for dyeing the hair.
It is known to bleach keratin fibers, and in particular human keratin fibers such as the hair, with bleaching compositions containing one or more oxidizing agents. Among the oxidizing agents conventionally used, there may be mentioned hydrogen peroxide, compounds capable of producing hydrogen peroxide by hydrolysis, such as urea peroxide, or persalts such as perborates, percarbonates and persulphates, hydrogen peroxide and persulphates being particularly preferred.
Bleaching compositions are provided mainly in the form of anhydrous products, powders or creams, containing alkaline compounds such as amines or alkali metal silicates, and a peroxygenated reagent such as ammonium or alkali metal persulphates, perborates or percarbonates which are diluted at the time of use with an aqueous hydrogen peroxide composition.
Bleaching compositions may also result from mixing, at the time of use, an anhydrous powder containing the peroxygenated reagent with an aqueous composition containing the alkaline compounds and another aqueous composition containing hydrogen peroxide.
To obtain a product for bleaching keratin fibers which is more effective in terms of lightening and/or speed, it is in theory possible to increase the hydrogen peroxide concentration in the aqueous hydrogen peroxide composition. However, a high hydrogen peroxide concentration can cause degradation of the keratin fibers and possibly skin irritation. Conventionally, in conventional bleaching compositions, the hydrogen peroxide concentration is therefore limited to 12% by weight, or even to 6% by weight.
Moreover, patent application EP 0,193,471 proposes bleaching the hair with an anhydrous hydrogen peroxide solution in an organic solvent.
There has also been proposed, in patent application WO 03/011216, a composition for bleaching the hair which is provided in the form of a direct or inverse emulsion containing an aqueous hydrogen peroxide solution and an organic phase comprising at least one perfluorinated compound.
However, the results obtained in terms of lightening are not yet satisfactory.